Substrate holding device and electric-circuit fabricating process

ABSTRACT

A substrate holding device for holding a ceramic substrate. The substrate holding device includes a receiving member and a clamping jaw which have respective contact surfaces brought into contact with the ceramic substrate, wherein the contact surfaces are constituted by elastically deformable portions. A variable flow regulator valve and an electromagnetically-operated proportional control valve are provided between an air source and a clamp cylinder which actuates the clamping jaws. A flow rate of air supplied to the clamp cylinder is controlled by the variable flow regulator valve and a control device which controls the variable flow regulator valve, such that movement velocity of the clamping jaws is gradually reduced in a final stage of the forward movement of the clamping jaw toward the receiving member. Further, a pressure of the air supplied to the clamp cylinder is controlled by the proportional control valve and the control device which controls the proportional control valve, such that the air pressure is set at a value suitable for the kind of ceramic substrate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a device for holding a ceramicsubstrate or other substrate made of a fragile material, for mounting anelectric or electronic component onto the substrate, for applying anadhesive into a desired spot or spots of the substrate, or for otherpurpose. The invention also relates to a process of fabricating anelectric circuit by using such a holding device.

[0003] 2. Discussion of Related Art

[0004] There is known an operation for fabricating a printed circuitsubstrate or other electric circuit, by mounting electric componentsonto a circuit substrate such as a printed wiring board. Such afabricating operation is commonly carried out by using a substrate worksystem equipped with a substrate holding device for holding the circuitsubstrate, a working head for achieving an operation in a predeterminedportion of the circuit substrate held by the substrate holding device,and a relative movement device for moving the substrate holding deviceand the working head relative to each other. As such a substrate worksystem, there is known an adhesive applying system and anelectric-component mounting system, for example. In the adhesiveapplying system, the working head takes the form of an applying head forapplying an adhesive to the circuit substrate. In the electric-componentmounting system, the working head takes the form of a mounting head formounting the electric component onto the circuit substrate.

[0005] It is common that the above-described substrate working system isequipped with a substrate clamping device which includes a metallicreceiving member and a metallic movable member adapted to force aperipheral or other portion of the circuit substrate against thereceiving member, for thereby clamping the circuit substrate. However,it is not easy to clamp the circuit substrate in an appropriate manner,particularly, where the circuit substrate is provided by afragile-material-made substrate such as a ceramic substrate madeprincipally of a ceramic material. The ceramic material or other fragilematerial is likely to be broken or damaged with substantially no plasticdeformation, if a large force or stress is applied to the circuitsubstrate. Therefore, where the circuit substrate is convexed, thecircuit substrate is likely to be damaged if the circuit substrate isintended to be straightened by forcing the circuit substrate to bedeformed in an amount too large for its elastic deformability. Further,there is a possibility that the circuit substrate might be damaged ifthe circuit substrate receives an excessively large load, for example,due to a shock generated when the circuit substrate is forced by themovable member against the receiving member.

SUMMARY OF THE INVENTION

[0006] The present invention was made in view of the above-describedbackground situation, and has an object of obtaining a substrate holdingdevice capable of holding a fragile substrate in an appropriate mannerwhile preventing the fragile from being damaged. The present inventionprovides the following modes in the form of a substrate holding deviceor a process of fabricating an electric circuit by using the substrateholding device. Each of the modes is numbered like the appended claimsand depends from the other mode or modes, as needed, for easyunderstanding of the present invention. It is to be understood that thetechnical features or any combinations thereof disclosed in the presentspecification is not limited to what are described in the followingmodes. It is to be further understood that a plurality of elements orfeatures included in any one of the following modes of the invention arenot necessarily provided all together, and that the invention may beembodied with selected one or ones of the elements or features describedwith respect to the same mode.

[0007] (1) A substrate holding device for holding a circuit substrate,the substrate holding device comprising:

[0008] a substrate clamping device including a receiving member and amovable member which forces a portion of the circuit substrate againstthe receiving member, for thereby clamping the circuit substrate,

[0009] wherein at least one of the receiving member and the movablemember has an elastically deformable portion formed of a rubber or itsequivalent material and provided by a contact portion thereof which isto be brought into contact with the circuit substrate.

[0010] The present substrate holding device is suitable for holding aceramic substrate or other substrate made of a fragile material. In thepresent substrate holding device, the contact portion of at least one ofthe receiving member and the movable member is provided by theelastically deformable portion which is formed of the rubber or itsequivalent material, thereby making it possible to avoid stressconcentration in a local portion or portions of a contact surface of thecircuit substrate at which the circuit substrate is brought into contactwith the above-described at least one of the receiving member and themovable member, and accordingly making it possible to avoid damaging ofthe circuit substrate. Even where the circuit substrate is upwardly ordownwardly convexed, a predetermined work can be satisfactorily achievedon the circuit substrate without damaging of the circuit substrate dueto an excessive deformation of the circuit substrate. In such a casewhere the circuit substrate is upwardly or downwardly convexed, it ispreferable that the contact portions of both of the receiving member andthe movable member are provided by the elastically deformable portions.However, the contact portions of both of the receiving member and themovable member do not have to be provided by the elastically deformableportion. That is, even where the contact portion of only one of thereceiving and movable members is provided by the elastically deformableportion, a possibility of damaging of the circuit substrate can be madesmaller as a result of a smaller amount of deformation of the circuitsubstrate, than where the contact portions of both of the receiving andmovable members are formed of metallic material. Thefragile-material-made substrate may be not only the ceramic substratebut also a glass substrate. In these days, a glass substrate is usedmainly for an inspection for checking positioning accuracy of theelectric components mounted on the substrate, but can be used for theother purpose.

[0011] It should be noted that the present substrate holding device iscapable of holding, for example, a synthetic-resin-made substrate, too.In a case where such a synthetic-resin-made substrate is held by thepresent substrate holding device, the present invention providessubstantially the same technical effects and advantages in greater orlesser degrees, as compared to a case where the fragile-material-madesubstrate is held by the substrate holding device. Further, thesubstrate holding device may be used for holding even a circuitsubstrate which is not likely to be damaged, namely, even where thetechnical advantages of the present invention are not appreciated somuch.

[0012] (2) A substrate holding device according to mode (1), wherein theelastically deformable portion is formed of a rubber or its equivalentmaterial which has an electric conductivity.

[0013] Since it is common that the receiving and movable members aremade of a metallic material, the circuit substrate can be prevented frombeing electrified where the elastically deformable portion is formed ofthe rubber having an electric conductivity. By preventingelectrification of the circuit substrate, it is possible to avoidsticking of dust to the circuit substrate, displacement of an electriccomponent mounted at a predetermined spot and a failure to mount anelectric component, which would be occurred due to static electricity.It is noted that a conductive passage such as a lead wire may beprovided to connect the elastically deformable portion having theelectric conductivity, with a main body of the device or other portionof the device made of a metallic material, where the receiving andmovable members are not made of a metallic material.

[0014] (3) A substrate holding device according to mode (1) or (2),comprising:

[0015] an actuator which actuates the movable member; and

[0016] a movement-velocity controlling device controlling a movementvelocity of the movable member actuated by the actuator.

[0017] The movement-velocity controlling device may be provided by a camdevice or other mechanically controlling device disposed between theactuator and the movable member. Further, the movement-velocitycontrolling device may be provided by an electrically controlling deviceor an actuator-actuation-velocity controlling device which controls anactuation velocity of the actuator so as to control the movementvelocity of the movable member. The feature described in this mode (3)is effectively applicable to a substrate holding device in which thefeature described in the above-described mode (1) is not included, i.e.,in which the elastically deformable portion is provided neither in themovable member nor in the receiving member.

[0018] (4) A substrate holding device according to mode (3), wherein themovement-velocity controlling device has a velocity reducing portionwhich reduces the movement velocity of the movable member in a finalstage of forward movement of the elastically deformable portion of themovable member toward the receiving member.

[0019] The reduction in the movement velocity of the elasticallydeformable portion of the movable member in the final stage of theforward movement makes it possible to reduce a dynamic load applied tothe circuit substrate upon contact of the movable and receiving memberswith the circuit substrate, thereby avoiding damaging of the circuitsubstrate upon the contact, irrespective of whether the circuitsubstrate held by the substrate holding device is substantially flat,upwardly convexed or downwardly convexed.

[0020] (5) A substrate holding device according to mode (4), wherein thevelocity reducing portion gradually reduces the movement velocity of themovable member to substantially zero.

[0021] It is also possible to adapt the velocity reducing portion toreduce the movement velocity of the movable member in two or more stepsin the final stage of the forward movement. However, it is preferablethat the movement velocity is continuously or gradually reduced tosubstantially zero, for effectively reducing the impact load.

[0022] (6) A substrate holding device according to any one of modes(3)-(5), wherein the actuator is an air cylinder,

[0023] and wherein the movement-velocity controlling device includes anair-flow-rate controlling device controlling a flow rate of air to besupplied to the air cylinder.

[0024] In the arrangement in which the actuator is provided by the aircylinder and in which the flow rate of the air supplied to the aircylinder is controlled, it is possible to easily control the movementvelocity of the movable member.

[0025] (7) A substrate holding device according to mode (6), wherein theair-flow-rate controlling device includes a variable flow regulatorvalve, and a regulator-valve controlling device which regulates thevariable flow regulator valve in a final stage of forward movement ofthe elastically deformable portion of the movable member toward thereceiving member.

[0026] In the substrate holding device of this mode, the movementvelocity of the movable member can be appropriately controlled by theair-flow-rate controlling device which is relatively simple inconstruction.

[0027] (8) A substrate holding device according to any one of modes(1)-(7), comprising:

[0028] an actuator which actuates the movable member; and

[0029] an actuation-force controlling device controlling an actuationforce with which the movable member is actuated by the actuator.

[0030] The arrangement of this mode makes it possible to avoid damagingof the circuit substrate due to an excessively large load. The featuredescribed in this mode (8) is effectively applicable to a substrateholding device in which at least one of the feature of theabove-described mode (1) and the feature of the above-described mode (3)is not included, i.e., in which the elastically deformable portion isprovided neither in the movable member nor in the receiving member,and/or in which the movement-velocity controlling device is notprovided.

[0031] (9) A substrate holding device according to mode (8), wherein theactuation-force controlling device controls the actuation force suchthat the actuation force is equalized to one of a plurality of differentamounts which are predetermined for a plurality of kinds of circuitsubstrates to be clamped.

[0032] The plurality of kinds of circuit substrates may include circuitsubstrates different from each other in material and/or dimension. Inthe substrate holding device of this mode, a contact pressure given bythe movable member can be controlled to a value suitable for the kind ofthe circuit substrate, thereby making it possible to prevent anexcessively large load from being applied to a local portion of thecircuit substrate and prevent the circuit substrate from being deformedin a large amount, whereby damaging of the circuit substrate can bereliably avoided.

[0033] (10) A substrate holding device according to mode (9), whereinthe actuator is an air cylinder,

[0034] and wherein the actuation-force controlling device includes anair-pressure controlling device controlling a pressure of air to besupplied to the air cylinder.

[0035] It is also possible that the actuator may be provided by anelectric motor so that the actuation force of the movable member iscontrollable by controlling an electric current to be supplied to theelectric motor, or by controlling an electric voltage to be applied tothe electric motor. However, the actuation force of the movable membercan be more easily controlled in the arrangement in which the actuatoris provided by the air cylinder and in which the pressure of air to besupplied to the air cylinder is controlled.

[0036] (11) A substrate holding device according to any one of modes(1)-(10), wherein the circuit substrate is a rectangular plate,

[0037] and wherein the receiving member and the movable member grip twoportions of the circuit substrate which portions are located along twomutually-parallel sides of the circuit substrate.

[0038] (12) A process of fabricating an electric circuit, by mounting aplurality of electric components onto a fragile-material-made substratesuch as a ceramic substrate by a mounting device, while fixing thesubstrate to the mounting device by causing an elastically deformableportion of a movable member formed of a rubber or its equivalentmaterial, to force a peripheral portion of the ceramic substrate againstan elastically deformable portion of a receiving member formed of arubber or its equivalent material.

[0039] It is also possible to provide only at least one of the movableand receiving members with the elastically deformable portion. Thesubstrate holding device with such an arrangement provides the technicaladvantage in a certain degree. However, the damaging of the circuitsubstrate can be more reliably avoided, where the both of the movableand receiving members are provided with the respective elasticallydeformable portions. The feature described in each of modes (2)-(11) isapplicable to the electric-circuit fabricating process of this mode(12).

BRIEF EXPLANATION OF THE DRAWINGS

[0040]FIG. 1 is a plan view schematically showing the entirety of anelectronic-component mounting system equipped with a substrate holdingdevice which is constructed according to an embodiment of the presentinvention;

[0041]FIG. 2 is a plan view of a horizontal-type substrate loadingdevice which is included in the above-described electronic-componentmounting system;

[0042]FIG. 3 is a front view of the above-described horizontal-typesubstrate loading device;

[0043]FIG. 4 is a cross sectional view taken along line 4-4 of FIG. 2;

[0044]FIG. 5 is a cross sectional view taken along line 5-5 of FIG. 2;

[0045]FIG. 6 is a plan view of the substrate holding device included inthe above-described electronic-component mounting system;

[0046]FIG. 7 is a front view of the above-described substrate holdingdevice;

[0047]FIG. 8 is a cross sectional view taken along line 8-8 of FIG. 6;

[0048]FIG. 9 is a view taken in the direction of arrow 9;

[0049]FIG. 10 is a cross sectional view taken along line 10-10 of FIG.6;

[0050]FIG. 11 is a cross sectional view taken along line 11-11 of FIG.6;

[0051]FIG. 12 is a circuit diagram indicating a control circuit of aclamp cylinder which is an element of the above-described substrateholding device;

[0052]FIG. 13 is a block diagram schematically showing portions of acontrol device which controls the above-described electronic-componentmounting system, which portions relate to the present invention;

[0053]FIG. 14 is a side view (partially in cross section) of a movablemember and a receiving member which are elements of a substrate holdingdevice constructed according to another embodiment of the presentinvention;

[0054]FIG. 15 is a perspective view of substrate supporting memberswhich are elements of a substrate holding device constructed accordingto still another embodiment of the present invention;

[0055]FIG. 16 is a front view in cross section of the above-describedsubstrate supporting members;

[0056]FIG. 17 is a front view in cross section showing a status in whicha ceramic substrate is supported by the above-described substratesupporting members;

[0057]FIG. 18 is a front view in cross section showing another status inwhich the ceramic substrate is supported by the above-describedsubstrate supporting members;

[0058]FIG. 19 is a plan view schematically showing the entirety of anelectronic-component mounting system equipped with a substrate holdingdevice which is constructed according to still another embodiment of thepresent invention;

[0059]FIG. 20 is a front view (partially in cross section) of theabove-described substrate holding device; and

[0060]FIG. 21 is a side view in cross section of a movable member and areceiving member which are elements of the above-described substrateholding device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] Hereinafter, an electronic-component mounting system equippedwith a substrate holding device which is constructed according to anembodiment of the present invention will be explained in detail on thebasis of the drawings. This electronic-component mounting system iscapable of carrying out an electric-circuit fabricating process which isan embodiment of the invention described in claim 12.

[0062] In FIG. 1, reference numerals 10, 12 and 14 denote acircuit-substrate transferring device, an electronic-component mountingdevice and an electronic-component supplying device, respectively. Theelectronic-component supplying device 14 includes component supplyingtables 20, 22 on each of which a plurality of electronic-componentsupplying units are mounted. These component supplying tables 20, 22 areadapted to be movable along guide rails 28 by respective feed screwmechanisms 24, 26. When each of the component supplying tables 20, 22has been positioned on a mounting position which is adjacent to theelectronic-component mounting device 12, electronic components aresupplied one after another to the electronic-component mounting device12 from the electronic-component supplying units. In the presentembodiment, each of the electronic-component supplying units is arrangedto feed a carrier tape which accommodates the electronic components.That is, the electronic components as the electric components aresupplied one after another to a component supplying portion, by a tapefeeding device in synchronization with rotation of an index of theelectronic-component mounting device 12. In the present embodiment inwhich the two component supplying tables 20, 22 are provided, it ispossible to successively supply a large number of electronic components,or successively supply many kinds of electronic components.

[0063] In an electronic-component mounting position, theelectronic-component mounting device 12 mounts the electronic componentsonto a circuit substrate which is held by a substrate holding device 30.In the present embodiment, as described later, the substrate holdingdevice 30 is suitable for holding the circuit substrate in the form of aceramic substrate 31 which is made principally of a ceramic material asa fragile material. The electronic-component mounting device 12 includesa plurality of suction heads each of which is adapted to suck and mountthe electronic component. The suction heads are attached to a rotarydisk which is intermittently rotatable, such that the suction heads areequiangular spaced from each other. The electronic components, suppliedfrom the electronic-component supplying device 14, are sucked andmounted onto the ceramic substrate 31, one after another, with theintermittent rotation of the rotary disk. Thus, the supply of theelectronic component and the mounting of the electronic component ontothe ceramic substrate 31 are made simultaneously.

[0064] A fiducial-mark camera 32 is provided in the electronic-componentmounting device 12. The electronic components are mounted onto theceramic substrate 31, after the fiducial-mark camera 32 takes images offiducial marks provided on the ceramic substrate 31. The fiducial-markcamera 32 takes the images of the fiducial marks one by one. However,the fiducial mark camera 32 may be modified to be capable of taking twoor more images of the fiducial marks at one time.

[0065] The circuit-substrate transferring device 10 includes a substrateloading device 36 and a substrate unloading device 38, which arearranged along a transferring direction in which the ceramic substrate31 is to be transferred. The substrate loading device 36 includes ahorizontally loading device 40 which substantially horizontally movesthe ceramic substrate 31 supplied from a circuit-substrate supplyingdevice (not shown), so as to load the ceramic substrate 31. Thesubstrate loading device 36 further includes a mounting device 42 whichreceives the ceramic substrate 31 loaded by the horizontally loadingdevice 40 and then moves the ceramic substrate 31 in a thicknessdirection of the ceramic substrate 31, so as to mount the ceramicsubstrate 31 onto the substrate holding device 30. The substrateunloading device 38 includes a horizontally unloading device 46 whichhorizontally moves the ceramic substrate 31 having the electroniccomponents mounted thereon, so as to unload the ceramic substrate 31.The substrate unloading device 38 further includes a demounting device48 which moves the ceramic substrate 31 in the thickness direction, soas to demount the ceramic substrate 31 from the substrate holding device30 and then hands over the ceramic substrate 31 to the horizontallyunloading device 46. The horizontally loading device 40, the mountingdevice 42, the horizontally unloading device 46 and the demountingdevice 48 are described in detail in JP-A-H11-145681 (publication ofJapanese Patent Application filed by the present applicant). Only partsof these devices relating to the present invention will be brieflyexplained.

[0066] The horizontally loading device 40 and the horizontally unloadingdevice 46 are disposed on a main body 50 (see FIG. 3) of theelectronic-component mounting system, such that the devices 40, 46 arespaced apart from each other in the transferring direction (X-axisdirection). As shown in FIG. 1, the horizontally loading device 40 has apair of main bodies 52, 54 which are arranged in the transferringdirection, as shown in FIG. 1. One 52 of the pair of main bodies 52, 54is fixed, while the other 54 is movable toward and away from the fixedmain body 52. Similarly, the horizontally unloading device 46 has a pairof main bodies 56, 58 which are arranged in the transferring direction.One 56 of the pair of main bodies 56, 58 is fixed, while the other 58 ismovable toward and away from the fixed main body 56. Each of themounting and demounting devices 42, 48 has a pair of main bodies, i.e.,a fixed main body and a movable main body which are arranged in thetransferring direction. The fixed main body 60 is commonly used for themounting and demounting devices 42, 48, and is provided to bridgebetween the fixed main bodies 52, 56 of the respective loading andunloading devices 40, 46. The movable main body 62 of the mountingdevice 42 is fixed to the movable main body 54 of the loading device 40,while the movable main body 64 of the demounting device 48 is fixed tothe movable main body 58 of the unloading device 46. Thus, since themain bodies 60, 62 of the mounting device 42 are respectively fixed tothe main bodies 52, 54 of the horizontally loading device 40 while themain bodies 60, 64 of the demounting device 48 are respectively fixed tothe main bodies 56, 58 of the horizontally unloading device 42, it ispossible to move the movable main bodies simultaneously with each other,for adjusting the spacing distance between the main bodies (as viewed ina width direction of the transferred substrate).

[0067] The horizontally loading device 40 includes, in addition to theabove-described main bodies 52, 54, a width adjusting device 74, ahorizontal movement device 76, a supporting-member elevating device 78and a horizontal movement stopping device 80. The width adjusting device74 includes two feed screw mechanisms 88, 90 and two guide rods 92, 94,as shown in FIG. 2. A rotation transmitting device 98 transmits therotation of a handle 96 which is provided in the horizontally unloadingdevice 46, to the feed screw mechanisms 88, 90. The rotationtransmitting device 98 includes a plurality of chains and sprocketswhich cooperate with each other to transmit the rotation of the handle96 to the feed screw mechanism 88, and the rotation transmitted to thefeed screw mechanism 88 is further transmitted to the feed screwmechanism 90 through a pair of sprockets 104, 106 and a chain 108. Therotations thus transmitted to the feed screw mechanisms 88, 90 cause themovable main bodies to be moved toward and away from the fixed mainbodies while being guided by the guide rods 92, 94. Thus, by rotatingthe handle 96, it is possible to change the spacing distance between themain bodies, as viewed in the width direction, in the horizontallyunloading device 46, the horizontally loading device 40, the mountingdevice 42 and the demounting device 48, simultaneously with each other.In the present embodiment, a drive source of width adjusting device 74is provided in the horizontally unloading device 46.

[0068] As shown in FIG. 5, the horizontal movement device 76 of thehorizontally loading device 40 includes a pair of substrate supportingmembers in the form of transferring belts 120, 122, guide plates 124,126 and transferring motors 128, 130. The transferring belt 120 is woundon a pair of pulleys which are rotatably attached to the fixed main body52, while the transferring belt 122 is wound on a pair of pulleys whichare rotatably attached to the movable main body 54. Each of the belts120, 122 is driven when the pulleys are rotated by the transferringmotors 128, 130. Thus, the ceramic substrate 31 supported by the belts120, 122 is moved in the horizontal direction while being guided by theguide plates 124, 126, so that the ceramic substrate 31 is loaded. Sincethe transferring motors 128, 130 are driven in synchronization with eachother, the pair of belts 120 are moved substantially concurrently witheach other at substantially the same velocity.

[0069] As shown in FIG. 4, the supporting-member elevating device 78 ofthe horizontally loading device 40 is adapted to elevate and lowersubstrate supporting members in the form of substrate supporting plates140. The supporting-member elevating device 78 includes an elevatingcylinder 142 and a substrate-supporting-plate elevating member 144. Thesupporting-member elevating device 78 is provided in a downstreamportion of the horizontally loading device 40 as viewed in thetransferring direction. The substrate-supporting-plate elevating member144 extends in a direction perpendicular to the transferring direction.The substrate-supporting-plate elevating member 144 is supported at itsopposite end portions by respective guide devices 146, 148, such thatits intermediate portion is opposed to a piston rod 150 of the elevatingcylinder 142.

[0070] When the piston rod 150 is elevated with actuation of theelevating cylinder 142, the substrate-supporting-plate elevating member144 is elevated while being guided by the guide devices 146, 148. Withthe elevation of the substrate-supporting-plate elevating member 144,substrate-supporting-plate supporting members 154 are elevated againstbiasing forces of respective coil springs 156 while being guided byrespective guide rods 158. The substrate supporting plates 140 are thuselevated as a result of the elevations of the substrate-supporting-platesupporting members 154.

[0071] When the piston rod 150 is lowered, the substrate supportingplates 140 and the substrate-supporting-plate elevating member 144 islowered owing to the biasing forces of the coil springs 156.

[0072] As shown in FIG. 3, the horizontal-movement stopping device 80 ofthe horizontally loading device 40 is adapted to stop the ceramicsubstrate 31 in an intermediate portion located between upstream anddownstream ends of the horizontally loading device 40 as viewed in thetransferring direction. Described specifically, in a case where two ormore ceramic substrates 31 are loaded, the stopping device 80 stops thesecond ceramic substrate 31 or each of the second and following ceramicsubstrates 31 in a predetermined intermediate position. In the presentembodiment, the stopping device 80 is, attached to a portion of thehorizontally loading device 40, which portion is changeable. Thus, it ispossible to stop the ceramic substrate 31 in a predeterminedintermediate position, providing a suitable spacing distance between theceramic substrate 31 in question and the adjacent ceramic substrate 31.The stopping device 80 includes an intermediate stopper 162, a stoppersupporting member in the form of a supporting plate 164, and anintermediate-stopper moving device 166 which is attached to thesupporting plate 164 and which moves the intermediate stopper movingdevice 166 between its operative and inoperative positions. Thesupporting plate 164 is attached to the main body 52 of the horizontallyloading device 40 through attaching devices 172 each of which includes abolt and a nut. The attached position of the stopping device 80 relativeto the main body 52 as viewed in the transferring direction isadjustable within a range corresponding to an elongated hole 170. Thisattached position of the stopping device 80 is determined depending uponthe length of the ceramic substrate 31 as measured in the transferringdirection. The intermediate-stopper moving device 166 includes a stoppercylinder 174.

[0073] As shown in FIG. 2, a downstream-end stopper 182 as a fixedstopper is provided in a downstream end portion of each of the mainbodies 52, 54 of the horizontally loading device 40. The horizontalmovement of the ceramic substrate 31, which has been first loaded, isstopped by the downstream-end stopper 182.

[0074] When the loading of the ceramic substrate 31 is initiated, theintermediate stopper 162 is positioned in its inoperative position. Whenthe transferring belts 120, 122 are driven, the first ceramic substrate31 is moved in the horizontal direction. The horizontal movement of thefirst ceramic substrate 31 is stopped by its abutting contact with thedownstream-end stopper 182. Subsequently, the intermediate stopper 162which is on the upstream side of the first ceramic substrate 31 is movedto its operative position by actuation of the stopper cylinder 174, sothat the next ceramic board 31 moved in the horizontal direction by thetransferring belts 120, 122 is stopped by the intermediate stopper 162.Meanwhile, the first ceramic substrate 31 brought into abutting contactwith the downstream-end stopper 182 is held in stationary. Thus, the twoceramic substrates 31 are supported on the transferring belts 120, 122such that the two ceramic substrates 31 are spaced apart from each otherby a spacing distance that is defined by the intermediate stopper 162.

[0075] The horizontally unloading device 46 includes a width adjustingdevice, a horizontal movement device, a supporting-member elevatingdevice and a horizontal-movement stopping device which are constructedas those of the horizontally loading device 40.

[0076] The horizontally loading device 40 includes a platevertical-stroke-ends sensor 192, a stopper operational-status sensor 194(see FIG. 13), a substrate in-position sensor 196 (see FIG. 3) and adeceleration sensor 198 (see FIG. 3). The plate vertical-stroke-endssensor 192 serves to detect whether the substrate supporting plate 140is positioned in its upper stroke end or lower stroke end. The stopperoperational-status sensor 194 serves to detect whether the intermediatestopper 162 is in its operative or inoperative position. The substratein-position sensor 196 serves to detect whether the ceramic substrate 31has been positioned in the downstream end or in the position defined bythe intermediate stopper 162. The deceleration sensor 198 serves todetect that the ceramic substrate 31 has arrived in positions in whichits horizontal movement should be decelerated. The substrate in-positionsensor 196 and the deceleration sensor 198 are attached to respectiveportions of the horizontally loading device 40, which portions areadjustable depending upon the size of the ceramic substrate 31 that isto be transferred. In order that the ceramic substrate 31 moved in thehorizontal direction is brought into abutting contact with theintermediate stopper 162 and the downstream-end stopper 182 at a reducedvelocity, the transferring motors 128, 130 are controlled such that thehorizontal movement of the ceramic substrate 31 is decelerated.

[0077] As shown in FIGS. 6 and 7, the substrate holding device 30includes a substrate holding portion 300 serving as a substrate clampingdevice, a holding-portion moving device 302, a holding-width adjustingguide device 304 and a holding-portion elevating device. Theholding-portion moving device 302 includes a driving motor 313 whichmoves an X-Y table 312 supporting a main body 310 of the substrateholding device 30. The X-Y table 312 is moved by the driving motor 313and other driving source, in the transferring direction (i.e., Xdirection) and the direction (i.e., Y direction) perpendicular to thetransferring direction, so that the main body 310 is moved in the X andY directions.

[0078] The main body 310 of the substrate holding device 30 is equippedwith the holding-portion elevating device which includes an elevatingmotor 306 (see FIG. 13), a driving pulley, a feed screw device 307, aplurality of driven pulleys 308 and a timing belt 309 (see FIG. 7), sothat a main body 314 of the substrate holding portion 300 is movedrelative to the main body 310 of the substrate holding device 30 in thevertical direction. With activation of the holding-portion elevatingdevice, the main body 314 of the substrate holding portion 300 can bepositioned in a substrate-mounting level in which the ceramic substrate31 is loaded from the substrate loading device 36, asubstrate-demounting level in which the ceramic substrate 31 is unloadedto the substrate unloading device 38 after the electronic componentshave been mounted onto the ceramic substrate 31, a horizontal movementlevel in which the ceramic substrate 31 is horizontally moved, and anelectronic-components mounting level in which the electronic componentsare mounted onto the ceramic substrate 31. The substrate holding portion300 includes a pair of clamp-type holding portions 316, 318 which haverespective main bodies 320, 322. The main body 320 of the holdingportion 316 is fixedly attached to the main body 314 of the substrateholding portion 300, while the main body 322 of the holding portion 318is movably attached to the same 314. Like the horizontally loadingdevice 40, the horizontally unloading device 46, the mounting device 42and the demounting device 48, the movable main body 322 is moved towardand away from the fixed main body 320 while being guided by theholding-width adjusting guide device 304 which includes guide rails. Thefixed main body 320 is fixed to the main body 314 of the substrateholding portion 300 through fixing devices 323, as shown in FIGS. 6 and7.

[0079] The clamp-type holding portion 316 includes the above-describedmain body 320, a rotary shaft 324 held by the main body 320 such thatthe rotary shaft 324 is rotatable relative to the main body 320, aplurality of clamping members 326 which are fixed to the rotary shaft324 such that the clamping members 326 are spaced apart from each otherby a suitable spacing distance, and a clamping-member driving device 328which rotates the rotary shaft 324. Similarly, the clamp-type holdingportion 318 includes the above-described main body 322, a rotary shaft324 held by the main body 322 such that the rotary shaft 324 isrotatable relative to the main body 322, a plurality of clamping members326 which are fixed to the rotary shaft 324 such that the clampingmembers 326 are spaced apart from each other by a suitable spacingdistance, and a clamping-member driving device 328 which rotates therotary shaft 324. The clamp-type holding portions 316, 318 are identicalwith each other except that the holding portion 316 is fixed to the mainbody 320 while the holding portion 318 is movable relative to the mainbody 322. Therefore, only the holding portion 318 will be explained, andexplanation of the holding portion 316 will not be provided.

[0080] The main body 322 of the clamp-type holding portion 318 is acomb-like body elongated in the transferring direction. As shown in FIG.11, the main body 322 has a substrate supporting surface 332 whichsupports a lower surface of the ceramic substrate 31, and a positioningsurface 334 which is brought into contact with a widthwise end surfaceof the ceramic substrate 31 for thereby positioning the ceramicsubstrate 31 in the widthwise direction. The substrate supportingsurface 332 of the main body 320 cooperates with clamping jaws 340 ofthe clamping members 326 to grip a corresponding one of two portions ofthe rectangular ceramic substrate 31 which portions are located alongtwo mutually-parallel sides of the rectangular ceramic substrate 31.Each of the clamping members 326 includes the clamping jaw 340, and amain body 341 which is formed integrally with the clamping jaw 340 andwhich is fitted on the rotary shaft 324 unrotatably and unmovablyrelative to the rotary shaft 324. The main body 322 and the clamping jaw340 have respective contact portions which are brought into contact withthe ceramic substrate 31. The contact portion of the main body 322includes the above-described substrate supporting surface 332, while thecontact portion of the clamping jaw 340 provides a distal end portion ofthe clamping jaw 340 which is opposed to the substrate supportingsurface 332. These contact portions of the main body 322 and theclamping jaw 340 constitute respective elastically deformable portions342, 344 each of which is formed of a rubber having a certain degree ofelectric conductivity. The rubber having the certain degree of electricconductivity is an example of a rubber or its equivalent material thatis suitable for forming the elastically deformable portions 342, 344.The provision of the elastically deformable portions 342, 344 makes itpossible to avoid stress concentration in a local portion or portions ofcontact surfaces of the ceramic substrate 31 at which the ceramicsubstrate 31 is brought into contact with the substrate supportingsurface 332 and the clamping jaw 340, and accordingly makes it possibleto avoid damaging of the ceramic substrate 31. Further, since theelastically deformable portions 342, 344 are made of the rubber havingthe electric conductivity, the ceramic substrate 31 can be preventedfrom being electrified while being clamped. It is noted that a coatinglayer 345 is formed on the positioning surface 334 and other portion ofthe main body 322, so that the main body 322 has an improved degree ofwear resistance. In the present embodiment, the coating layer 345 isprovided by a diamond coating (DLC).

[0081] The rotary shaft 324 is supported at its opposite end portions bythe main body 322 such that the rotary shaft 324 is rotatable relativeto the main body 322, and is supported at its intermediate portion bythe main body 322 via a bearing 346. The clamping-member driving device328 is provided in one of opposite end portions of the main body 322. Asshown in FIG. 9, the clamping-member driving device 328 includes a clampcylinder 350 as an actuator, and a drive lever 352. As is apparent fromFIG. 12 which schematically shows its construction, the clamp cylinder350 includes a cylindrical housing, a piston 353 that is slidablymovable within the cylindrical housing, and a piston rod 354 thatprotrudes from the piston 353 outwardly of the cylindrical housing. Thepiston rod 354 has a distal end portion to which an end portion of thedrive lever 352 is attached such that the drive lever 352 is pivotablerelative to the piston rod 354. The other end portion of the drive lever352 is engaged with the rotary shaft 324. That is, one 356 of theopposite end portions of the rotary shaft 324 has two mutually-parallelsurfaces, so that the end portion 356 of the rotary shaft 324 is grippedby the other end portion of the drive lever 352. When the piston rod 354is moved in the vertical direction with actuation of the clamp cylinder350, the drive lever 352 is pivoted about the axis of the rotary shaft324 whereby the rotary shaft 324 is rotated. With the rotation of therotary shaft 324, the substrate holding portion 300 as the substrateclamping device is switched between its clamping position and unclampingposition. In the holding portion 318, each clamping jaw 340 is moved toits clamping position when the piston rod 354 is retracted (as indicatedby the solid lines in FIG. 9), while each clamping jaw 340 is moved toits unclamping position when the piston rod 354 is extended (asindicated by the two-dot chain lines in FIG. 9). In the holding portion316, on the other hand, each clamping jaw 340 is moved to its clampingposition when the piston rod 354 is extended (as indicated by the solidlines in FIG. 9), while each clamping jaw 340 is moved to its clampingposition when the piston rod 354 is retracted (as indicated by thetwo-dot chain lines in FIG. 9). Since the clamp cylinder 350 is attachedto the main body 322 such that the clamp cylinder 350 is pivotablerelative to the main body 322, it is possible to clamp the ceramicsubstrate 31 with a substantially constant force even if the thicknessof the ceramic substrate 31 is variable. Further, the pivot movement ofthe clamp cylinder 350 assures smooth movement of the piston rod 354relative to the cylindrical housing. As shown in FIGS. 9 and 10, theclamp cylinder 350 is attached to the main body 322 such that itsportion is accommodated in an accommodating portion formed in the mainbody 322, so that the pivot movement of the clamp cylinder 350 islimited by an inner surface 357 of the accommodating portion.

[0082] Each of the clamp cylinders 350 is a double acting cylinder, asshown in FIG. 12 which illustrates one of the clamp cylinders 350constitutes the holding portion 318. A selected one of two solenoids ofan electromagnetically-operated directional control valve 364 isenergized so that an air is supplied from an air source 362 to aselected one of a head-side chamber 360 and a rod-side chamber 361 whilethe air is discharged from the other of the chambers 360, 361, wherebythe piston rod 354 is extended and retracted for pivoting the drivelever 352. A variable flow regulator valve 366 is provided in an airpassage 365 which communicates the head-side chamber 360 with the airsource 362, while an electromagnetically-operated proportional controlvalve 368 is provided in an air passage 367 which communicates therod-side chamber 361 with the air source 362. Since the above-describedelectromagnetically-operated directional control valve 364, the variableflow regulator valve 366 and the electromagnetically-operatedproportional control valve 368 are provided by known valves, theirdetail explanations are not provided. A portion of the air passage 365in which the variable flow regulator valve 366 is provided has a crosssection whose area is variable by varying an amount of electric currentsupplied to a solenoid of the variable flow regulator valve 366. Thatis, by varying the amount of the supplied electric current, it ispossible to vary a flow rate of the air flowing through the air passage365. Thus, it is possible to control the flow rate of the air dischargedfrom the head-side chamber 360 of the clamp cylinder 350, and to controlthe flow rate of the air supplied to the rod-side chamber 361, therebycontrolling an actuation velocity of the clamp cylinder 350, namely,controlling a velocity of movement of the clamping jaw 340 toward itsclamping position. A valve opening pressure of theelectromagnetically-operated proportional control valve 368 can bevaried by varying an amount of electric current supplied to a solenoidof the proportional control valve 368. Thus, it is possible to control apressure value of the air supplied to the rod-side chamber 361 of theclamp cylinder 350, thereby controlling an actuation force of the clampcylinder 350, namely, controlling a clamping force of the clamping jaw340. The clamping force of the clamping jaw 340 may be changed suitablydepending upon the thickness and material of the ceramic substrate 31.In the present embodiment, the clamping force is controlled to beequalized to a selected one of a plurality of different amounts whichare predetermined for a plurality of kinds of ceramic substrates 31. Itis noted that the variable flow regulator valve 366 provided in the airpassage 365 may be replaced with a variable flow regulator valve whichis provided between the proportional control valve 368 and the rod-sidechamber 36 in the air passage 367. Also in this modified arrangement,the flow rate of the air supplied to the rod-side chamber 361 can becontrolled. In the holding portion 316 whose control circuit forcontrolling the clamp cylinder 350 is not illustrated, theelectromagnetically-operated proportional control valve 368 is providedin the air passage 365 which communicates the head-side chamber 360 withthe air source 362, while the variable flow regulator valve 366 isprovided in the air passage 367 which communicates the rod-side chamber361 with the air source 362. This control circuit of the holding portion316 may be modified such that a variable flow regulator valve and anelectromagnetically-operated proportional control valve are provided inthe air passage 365 and such that the proportional control valve ispositioned between the variable flow regulator valve and the air source362. The control circuit of the holding portion 316 is different fromthat of the holding portion 318 only in the arrangements of the variableflow regulator valve and the proportional control valve, but is similarwith that of the holding portion 318 in that the movement velocity andthe clamping force of the clamping jaw 340 are controlled.

[0083] When the ceramic substrate 31 is clamped by the clamp-typeholding portions 316, 318 of the substrate holding portion 300, apositioning pin 370 is introduced in a hole formed through the ceramicsubstrate 31 while a backup pin 372 as a supporting member is held incontact with a surface (supported surface) of the ceramic substrate 31that is opposite to a surface (work surface) onto which the electroniccomponents are to be mounted, as shown in FIG. 8. The backup pin 372 isfixed to a pin supporting member 374 which is also adapted to bevertically movable.

[0084] The present electronic-component mounting system is controlled bya control device 380 which is shown in FIG. 13. The control device 380is principally constituted by a computer 390 including a processing unit(PU) 382, a read only memory (ROM) 384, a random access memory (RAM) 386and a bus interconnecting those elements 382, 384 and 386. To the bus,there is connected an input-output interface 392 to which are connectedvarious sensors such as the plate vertical-stroke-ends sensor 192, thestopper operational-status sensor 194, the substrate in-position sensor196 and the deceleration sensor 198. To the input-output interface 392,there are also connected the transferring motors 120, 122, the solenoidsof (the control valve of) the elevating cylinder 142 and (the controlvalve of) the stopper cylinder 174, the elevating motor 306, the drivingmotor 313, and the solenoids of the electromagnetically-operateddirectional control valve 364, the variable flow regulator valve 366 andthe electromagnetically-operated proportional control valve 368 of theclamp cylinder 350, through respective driver circuits 394. To theinput-output interface 392, there are also connected the fiducial-markcamera 32 through a controller circuit 396.

[0085] In the electronic-component mounting system constructed asdescribed above, the ceramic substrate 31 is loaded to the substrateholding device 30 by the substrate loading device 36. While the ceramicsubstrate 31 is supported by the substrate supporting surfaces 332 ofthe respective main bodies 320, 322 of the substrate holding device 30,the clamping jaws 340 are pivoted with activations of theclamping-member driving devices 328, whereby the clamping jaws 340 arebrought into contact with the ceramic substrate 31. In this instance,the ceramic substrate 31 are gripped at its opposite surfaces by theelastically deformable portions 342 of the substrate supporting surfaces332 and the elastically deformable portions 344 of the clamping jaws340, whereby the ceramic substrate 31 is fixed to the substrate holdingdevice 30. The substrate holding portion 300 is movable together withthe X-Y table 312 in the transferring direction (X-axis direction) andthe direction (Y-axis direction) perpendicular to the transferringdirection, so that the main body 310 of the substrate holding portion300 can be moved in the X-axis and Y-axis directions. The substrateholding portion 300 can be moved to be positioned in theelectronic-component mounting position in which the electronic-componentmounting device 12 is operated to mount the electronic components ontothe ceramic substrate 31 supported by the substrate holding portion 300,whereby a printed circuit board as the electric circuit is fabricated.

[0086] The movement velocity of the clamping members 326 is controlledby the control device 380 which controls the flow rate of the airsupplied to the clamp cylinder 350. Described specifically, the crosssectional area of the air passage of the variable flow regulator valve366 is reduced in a final stage of forward movement of the clampingmembers 326 toward the ceramic substrate 31, for thereby controlling theflow rate of the air supplied to the rod-side chamber 361 so that theforward movement velocity of the clamping members 326 is graduallyreduced. Owing to the gradual reduction in the forward movement velocityof the clamping members 326, the clamping jaws 340 can be brought intocontact with the ceramic substrate 31 at a reduced velocity. Further,the control device 380 controls the pressure of the air supplied to theclamp cylinder 350, on the basis of the material and thickness of theceramic substrate 31, such that a suitable load is applied to theceramic substrate 31 upon the contact of the clamping members 326 withthe ceramic substrate 31.

[0087] In the present embodiment, the substrate supporting surface 332of each of the main bodies 320, 322 as a receiving member and each ofthe clamping jaws 340 as a movable member have respective contactportions which are brought into contact with the ceramic substrate 31.Since the contact portions of the substrate supporting surface 332 andthe clamping jaw 340 are provided by the elastically deformable portions342, 344, respectively, which are formed of a rubber or its equivalentmaterial having a certain degree of electric conductivity, it ispossible to appropriately hold the ceramic substrate 31, i.e., a kind offragile-material-made circuit substrate that is easily damaged, withouta risk of damaging of the substrate 31. Further, the clamp cylinder 350as an actuator serving to pivot the clamping jaws 340 is controlled insuch a manner that reduces the velocity of the movement of theelastically deformable portions 344 toward the substrate supportingsurface 332, thereby making it possible to reduce the load applied tothe ceramic substrate 31 upon contact of the clamping jaws 340 and thesubstrate supporting surface 332 with the ceramic substrate 31. Thisreduction in the movement velocity of the clamping jaws 340 alsocontributes to the prevention of damaging of the ceramic substrate 31.Still further, the pressure of the of the air supplied to the clampcylinder 350 is controlled on the basis of the material and size of theceramic substrate 31 such that a suitable load is applied to the ceramicsubstrate 31 upon the contact of the clamping jaws 340 with the ceramicsubstrate 31, whereby the ceramic substrate 31 can be held with asuitable force.

[0088] In the present embodiment, the variable flow regulator valve 366cooperates with a portion of the control device 380, which portionfunctions as a regulating device to regulate the variable flow regulatorvalve 366 in the final stage of the above-described forward movement(which portion constitutes a velocity reducing portion for reducing themovement velocity of the clamping jaws 340 in the final stage of theforward movement), to constitute an air-flow-rate controlling device asa kind of movement-velocity controlling device. Further, theelectromagnetically-operated proportional control valve 368 cooperateswith a portion of the control device 380, which portion controls thesolenoid of the proportional control valve 368, to constitute anair-pressure controlling device as an actuation-force controllingdevice. It is noted that a damaging of a fragile-material-made substratesuch as the ceramic substrate can be prevented to some degree even wherethe substrate holding device is provided with at least one of thearrangement that the elastically deformable portions are provided in themovable and receiving members, the arrangement that the movementvelocity of the movable member is reduced in the final stage of itsforward movement, and the arrangement that the air pressure iscontrolled such that a suitable load is applied to the ceramic substrateupon the contact of the movable member with the ceramic substrate. It isalso noted that the actuator for actuating the clamping jaws 340 can beprovided by an electric motor in place of the air cylinder. However,where the actuator is provided by the air cylinder as in the presentembodiment, it is possible to reduce a required cost more satisfactorilythan where the actuator is provided by the electric motor.

[0089] Like the positioning surfaces 334 of the main bodies 320, 322,side surfaces of the main bodies of the horizontally loading device 38and the horizontally unloading device 40, i.e., guide surfaces forguiding the ceramic substrate 31 may be coated with a diamond coating,so that the guide surfaces have an improved degree of wear resistance.Further, at least one of the intermediate stopper 162 and thedownstream-end stopper 182 may be provided with an elasticallydeformable portion, like the above-described elastically deformableportions 342, 344, which is formed of an electrically-conductive rubberor its equivalent material, for thereby alleviating an impact generatedupon contact of the stopper 162 and/or stopper 188 with the ceramicsubstrate 31 so as to avoid damaging of the ceramic substrate 31.

[0090] As shown n FIG. 14, each of the clamping jaws 340 may include athickness reduction portion 400 which has a smaller thickness than theother portion of the clamping jaw 340. The thickness reduction portion400 is provided by a connecting portion in which the clamping jaw 340 isconnected with the main body portion 341, namely, provided by a proximalend portion of the clamping jaw 340 that is opposite to a distal endportion of the clamping jaw 340 in which the elastically deformableportion 344 is provided. The thickness reduction portion 400 iseffective to further reduce a load applied to the ceramic substrate 31upon the contact of the clamping jaw 340 with the ceramic substrate 31,thereby making it possible to more satisfactorily hold the ceramicsubstrate 31 without a risk of damaging of the ceramic substrate 31.

[0091] The supporting member for supporting the lower surface of theceramic substrate 31 may be provided by a plurality of substratesupporting members 410, 412 which are formed of a rubber or itsequivalent material, as shown in FIGS. 15-18. The supporting members410, 412 are described in detail in the specification of the JapanesePatent Application 2001-95550, which has been filed by the presentapplicant and has not been published yet. In the present embodiment,each of the supporting members 410, 412 is formed of a vibration dampingrubber. Described specifically, the vibration damping rubber has a lossfactor or loss tangent tan δ not smaller than 0.5, as measured when therubber is subjected to vibration of 110 Hz at a temperature of 20° C.This vibration damping rubber exhibits an excellent impact and vibrationabsorbing ability, and reacts little to an external force appliedthereto so as to absorb the external energy. As such a vibration dampingrubber, it is possible to employ a commercially available damping rubber(e.g., “HANENITE” manufactured by NAIGAI Co., Ltd.). This vibrationdamping rubber has physical properties and durability comparable tothose of standard rubbers, and exhibits an excellent vibration dampingability at an ordinary temperature range (5-35° C.), and an impactresilience smaller than 10%. Further, this vibration damping rubber hasa high degree of moldability as standard rubbers, and is firmlyadherable to a metal member. Still further, where this vibration dampingrubber is provided in the form of a sheet, it can be easily cut, blankedor punched.

[0092] Each of the supporting members 410, 412 consists of a verticallyextending columnar member whose cross sectional shape is constant asviewed in its axial direction, as shown in FIG. 16. Each supportingmember 412 has a diameter larger than that of each supporting member410, and a smaller height (axial length) than that of each supportingmember 410. Each supporting member 410 and each supporting member 412have respective upper end surfaces 420, 422. Each supporting member 412is adapted to have a compression modulus higher than that of eachsupporting member 410. In the present embodiment, the material formingeach supporting member 412 has a higher degree of hardness than thematerial forming each supporting member 410 so that the compressionmodulus of each supporting member 412 is made larger than that of eachsupporting member 410. As shown in FIG. 16, the supporting members 410,412 are regularly arranged on a holding surface 428 which is provided byan upper surface of a holding plate 426 (and which is to be broughtparallel with the lower surface of the ceramic substrate 31), such thateach of the supporting members 410 is adjacent to a corresponding one ofthe supporting members 412. In the present embodiment, the holdingsurface 428 has a plurality of sections in the supporting members 410,412 are arranged in accordance with a predetermined pattern, so that theplurality of sections of the holding surface 428 have the samearrangement of the supporting members 410, 412. Described morespecifically, the supporting members 410, 412 are arranged on theholding surface 428 in a zigzag or staggered pattern, as shown in FIG.15. However, the supporting members 410, 412 do not have to be arrangednecessarily in the staggered pattern, but may be otherwise arrangeddepending upon the substrate to be supported. The holding plate 426, onwhich the supporting members 410, 412 are arranged, is fixed to the pinsupporting member 374, such that the holding plate 426 is positioned ina predetermined position. Each of the supporting members 410, 412 doesnot have to be necessarily formed of the vibration damping rubber, butmay be formed of other material such as a foamed material.

[0093] The supporting members 410, 412 may be fixed to the holding plate426 by a boding agent or other suitable means. In the presentembodiment, the holding plate 426 has a plurality of receiving holes430, 432 which are formed in the holding surface 428, as shown in FIG.16, such that the receiving holes 430, 432 are arranged in a staggeredpattern. Each of the receiving holes 430 has an inside diameter which issmaller than that of each of the receiving holes 432 and which isslightly larger than the outside diameter of each of the supportingmembers 410. Each of the receiving holes 432 has an inside diameterwhich is slightly larger than the outside diameter of each of thesupporting members 412. The supporting members 410, 412 are fitted, attheir respective proximal end portions, into the receiving holes 430,432, with the proximal end portions being bonded to the receiving holes430, 432, whereby the supporting members 410, 412 are fixed to theholding plate 426. It is noted that the supporting members 410, 412 maybe press-fitted into the receiving holes 430, 432, so that thesupporting members 410, 412 can be fixed to the holding plate 426without using a boding agent.

[0094] The ceramic substrate 31 can be reliably supported by thesupporting members 410, 412, even where the ceramic substrate 31 isupwardly or downwardly convexed. Where the lower surface of the ceramicsubstrate 31 is substantially flat, or where the lower surface isdownwardly convexed as shown in FIG. 17, the ceramic substrate 31 issupported at the lower surface by the upper end surfaces 420, 422 of thesupporting members 410, 412, with the supporting members 410 beingelastically compressed. In this instance, both of the upper end surfaces420, 422 of the supporting members 410, 412 are held in contact with thelower surface of the ceramic substrate 31. Where the ceramic substrate31 is upwardly convexed as shown in FIG. 18, on the other hand, theceramic substrate 22 is supported at the lower surface by the upper endsurfaces 420 of the supporting members 410. In this instance, only theupper end surfaces 420 of the supporting members 410 are held in contactwith the lower surface of the ceramic substrate 31.

[0095] The ceramic substrate 31 tends to be subjected to vibration, forexample, when the electric component is brought into abutting-contactwith the ceramic substrate 31 as a result of the downward movement ofthe suction head, or when the ceramic substrate 31 is moved and stoppedby the X-Y table 312. However, the vibration applied to the ceramicsubstrate 31 is damped or absorbed, whereby the ceramic substrate 31 isprevented from being vibrated, or vibration of the ceramic substrate 31is rapidly settled or stopped even if the ceramic substrate 31 issomewhat vibrated. That is, the ceramic substrate 31 is not vibrated atleast at a point of time at which the electric component is mounted ontothe upper surface of the ceramic substrate 31, whereby the electriccomponent is mounted in a desired spot of the upper surface with highaccuracy. Further, the ceramic substrate 31 can be brought into contactat the lower surface with the supporting members 410, 412, without alarge compressive stress being concentrated in a local portion of eachof the upper end surfaces 420, 422 of the supporting members 410, 412,whereby the lower surface of the ceramic substrate 31 is reliablypositioned in a desired position, making it possible to accurately mountthe electric component on the upper surface of the ceramic substrate 31without a risk of failure in mounting of the electric component onto theceramic substrate 31. The supporting members 410, 412 are capable ofsupporting the ceramic substrate 31 without forcing the ceramicsubstrate 31 to be excessively deformed, namely, without providing arisk of fracture of the ceramic substrate 31 even if the ceramicsubstrate 31 is upwardly or downwardly convexed rather than flat. Wherethe ceramic substrate 31 is upwardly convexed, the ceramic substrate 31is supported by only the contacts of the upper end surfaces 420 of thesupporting members 410. However, also in this case, the vibration of theceramic substrate 31 is satisfactorily reduced. Still further, in thepresent embodiment in which the plurality of supporting members 410, 412are arranged in the staggered pattern, the ceramic substrate 31 can besupported, at its plurality of portions which are distributed evenlyover the entirety of the ceramic substrate 31 and which are distant fromeach other by a minimized distance, by the supporting members 410, 412,whereby the ceramic substrate 31 can be supported while beingsubstantially flattened.

[0096] An electronic-component mounting system equipped with a substrateholding device which is constructed according to another embodiment ofthe present invention will be explained in detail on the basis of thedrawings. In FIG. 19, reference numerals 510, 512 denote a componentmounting device and a component supplying device, respectively. Thecomponent mounting device 10 is equipped with an index table 514 whichis intermittently rotatable about a vertical axis line. The index table514 has a plurality of suction heads 516 each of which is a kind ofmounting head (working head) and is capable of sucking and holding theelectric component by applying a negative air pressure to the electriccomponent. The index table 514 holds the suction heads 516 such that thesuction heads 516 are equi-angularly spaced from one another about thevertical axis line. The index table 514 is intermittently rotated by anintermittently rotating device (not shown) including a cam, a camfollower, a rotary shaft, and an indexing servomotor for rotating thecam. With the intermittent rotation of the index table 514, thecomponent suction heads 516 are sequentially moved to each of aplurality of operation positions such as a component sucking position(i.e., a component picking position), a component-posture detectingposition, a component-posture correcting position, and a componentmounting position. Each of the suction heads 516 is positioned in theselected one of the operating positions, so that the suction head 516carries out the corresponding operation in the position. When thesuction head 516 is positioned in the component mounting position, forexample, the suction head 516 mounts the electric component on a printedcircuit board 522. It is noted that the printed circuit board 522, as asort of circuit substrate, consists of a ceramic substrate madeprincipally of a fragile material in the form of a ceramic material inthe present embodiment. The printed circuit board 522 will be referredto as “ceramic substrate 522” in the following descriptions.

[0097] The component supplying device 512 has a plurality of componentfeeders 532 each of which is mounted on a feeder supporting table 530.The component feeders 532 are supported on the supporting table 530 suchthat component-supply portions of the respective feeders 532 arearranged along a straight line on a horizontal plane (a directionparallel to this straight line will be referred to as the “X-axisdirection”). As a ball screw 536 is rotated by an X-axis servomotor 538,the feeder supporting table 530 is moved in the X-axis direction whilebeing guided by a pair of guide rails 540. Thus, the component supplyingportion of a selected one of the component feeders 532 is moved to acomponent supplying position. The ball screw 536 and the X-axisservomotor 538 cooperate with each other to provide a table movingdevice for moving the feeder supporting table 530. In the presentembodiment, each of the component feeders 532 includes a tape feedingdevice as a sort of component feeding device, and a tape-reel holdingdevice as a sort of component storing device, and supplies a pluralityof electric components by an electric-component carrier tape.

[0098] The ceramic substrate 522 is supported by a substrate positioningand supporting device 546 including an X-Y table 544, and is moved to adesired position on an X-Y plane by the substrate positioning andsupporting device 546. The ceramic substrate 522 is loaded by asubstrate loading device (not shown), onto the substrate positioning andsupporting device 546 which is disposed together with the componentmounting device 510 and the component supplying device 512 on a base550. The ceramic substrate 522 is carried or unloaded by a substrateunloading device (not shown) from the substrate positioning andsupporting device 546. The substrate loading and unloading devicesinclude respective conveyor belts for conveying the ceramic substrate522 in the X-axis direction. As shown in FIG. 19, the X-Y table 544includes a ball screw 552 provided on the base 50, an X-axis servomotor554 for rotating the ball screw 552, an X table 558 which is to be movedin the X-axis direction, a ball screw 560 provided on the X table 558, aY-axis servomotor 562 for rotating the ball screw 560, and a Y table 566which is to be moved in a Y-axis direction. As the ball screw 552 isrotated by the X-axis servomotor 554, the X table 558 is moved in theX-axis direction while being guided by a pair of guide rails 556.Similarly, as the ball screw 560 is rotated by the Y-axis servomotor562, the Y table 566 is moved in the Y-axis direction while being guidedby a pair of guide rails 564. Each of the servomotors is a sort ofelectric motor as an actuator, and is an electric rotary motor which isprecisely controllable with respect to its rotation angle or amount. Theservomotors may be replaced with stepping motors, and the electricrotary motors may be replaced with linear motors.

[0099] As shown in FIG. 20, on the Y table 566, there is provided afirst elevator table 570 such that the first elevator table 570 isimmovable in the X-axis and Y-axis directions relative to the Y table566 and is movable in a vertical direction, i.e., a Z-axis directionperpendicular to the X-axis and Y-axis directions relative to the Ytable 566. The Y table 566 has a pair of through-holes 572, 574 whichare formed through its thickness in the vertical direction. A pair ofrods 576, 578 are provided to extend through the respectivethrough-holes 572, 574 such that each of the rods 576, 578 is movable inits axial direction relative to a corresponding one of the holes 576,578. The first elevator table 570 is fixed to respective upper endportions of the two rods 576, 578 that project upwardly from the Y table566.

[0100] The rods 576, 578 have respective lower end portions whichproject downwardly from the Y table 566 and which are connected to eachother though a connection bar 580. Compression coil springs 582(hereinafter referred simply as to “springs 582”) each serving as anelastic member as a sort of biasing device are fitted on the respectivelower end portions of the rods 576, 578 that project downwardly from theY table 566. The springs 582 have respective lower ends which are seatedon the connection bar 580. Owing to biasing forces of the springs 582,the first elevator table 570 is held in its lower movement end positionin which the first elevator table 570 is held in contact with stoppers584 provided on the Y table 566. On the base 550, there is provided anair cylinder 586 as a sort of fluid-pressure-operated cylinder as anactuator. The connection bar 580 can be lifted up by an adjusting bolt588 fixed to a piston rod of the air cylinder 586, so that the firstelevator table 570 is moved to its upper movement end position in whichthe first elevator table 570 is separated from the Y table 566 by apredetermined distance in the upward direction.

[0101] On the first elevator table 570, there are provided a fixed guide590 and a movable guide 592. Each of the fixed and movable guides 590,592 consists of an elongated member having a rectangular cross section.The fixed and movable guides 590, 592 include respective hold-downportions 594, 596 projecting from their respective upper end portions.The fixed guide 590 is fixed to a plate-like supporting member 598 suchthat the fixed guide 590 extends parallel to the X-axis direction. Thesupporting member 598 is fixed to one of two sides of the first elevatortable 570 that are parallel to the X-axis direction, such that thesupporting member 598 extends parallel to the X-axis direction. Themovable guide 592 is fixed to another supporting member 600. Two slidemembers (not shown) are fitted in respective grooves which are formed inan upper surface of the first elevator table 570 and which are spacedapart from each other in the X-axis direction, such that the two slidemembers are movable in the Y-axis direction. The supporting member 600is fixed at its lengthwise opposite end portions to respective upper endportions of the two slide members, so that the supporting member 600extends parallel to the X-axis direction and accordingly the movableguide 592 also extends parallel to the X-axis direction. With themovement of the slide members, the movable guide 592 is moved toward andaway from the fixed guide 590, whereby a width for guiding the ceramicsubstrate 522 is adjusted.

[0102] Belt guides 604 are fixed, below the fixed and movable guides590, 592, to upper end portions of inner surfaces of the respectivesupporting members 598, 600 which surfaces are opposed to each other.Endless conveyor belts 606 are wound on the respective belt guides 604,and are driven in synchronization with each other by a belt drive device(not shown) including a drive motor as an actuator. Projecting members610 are fitted in the respective supporting members 598, 600, such thateach of the projecting members 610 is movable upwardly and downwardly.Each of the projecting members 610 consists of a plate-like member whichis elongated in the X-axis direction, and is located inside acorresponding one of the conveyor belts 606 (on one of opposite sides ofthe corresponding conveyor belt 606 that is closer to the other conveyorbelt 606). Each projecting member 610 is biased downwardly by a coilspring 612. The end of downward movement of each projecting member 610by the biasing force of the corresponding spring 612 is defined by astopper (not shown). In the state in which the projecting members 610are held in their lower movement end position, upper ends of theprojecting members 610 are substantially level with respective upperrunning portions (upper flat or straight portions) of the endlessconveyor belts 606. Engaging pins 614 are fixed to opposite ends of eachprojecting member 610, respectively, that are distant from each other inthe X-axis direction, such that each of the engaging pins 614 extendsdownwardly.

[0103] In the state in which the first elevator table 570 is held in itslower movement end position as shown in FIG. 20, the first elevatortable 570 and the ceramic substrate 522 placed on the first elevatortable 570 are positioned below the above-described board loading andunloading devices, and are moved together with the Y table 566 in theX-axis and Y-axis directions without being interfered by the boardloading and unloading devices. The X table 558 has an opening 616 whichis elongated in the Y-axis direction and which permits the rods 576, 578(projecting downwardly from the Y table 566) and the connection bar 580,to be moved together with the Y table 566 in the Y-axis direction.

[0104] In the state in which the first elevator table 570 is held in itshome position (in which the first elevator table 570 is aligned with theboard loading and unloading devices as viewed in the Y-axis direction,is positioned between the board loading and unloading devices as viewedin the X-axis direction, and is held in its upper movement end positionby the air cylinder 586), the height position of board-convey surfacesof the conveyor belts 606 that are defined by respective upper surfacesof the respective upper running portions of the conveyor belts 606 isthe same as the height position of board-convey surfaces of conveyorbelts of the board loading device that are defined by upper surfaces ofrespective upper running portions of the belts, and the height positionof board-convey surfaces of conveyor belts of the board unloading devicethat are defined by upper surfaces of respective upper running portionsof the belts. That is, at this home position, the first elevator table570 receives the substrate 522 from the board loading device anddischarges the substrate 522 to the board unloading device.

[0105] On the first elevator table 570, there is provided a secondelevator table 620 consisting of a plate-like member, such that thesecond elevator table 620 can be elevated and lowered. A pair of guiderods 622 serving as guide members are fixed to a lower surface of thesecond elevator table 620. The guide rods 622 are fitted in respectiveguide bushings 624 which are fixed to a lower surface of the firstelevator table 570, such that each of the guide rods 622 is movable inits axial direction relative to a corresponding one of the guidebushings 624. The guide bushings 624 are accommodated in respectiveholes formed through the thickness of the Y table 566, such that each ofthe bushings 624 is movable upwardly and downwardly. A piston rod 628 ofan air cylinder 626 as a sort of fluid-pressure-operated actuator as adrive source, and also as a sort of fluid-pressure-operated cylinderdevice, is fixed to the lower surface of the second elevator table 620.The air cylinder 626, which is of a single action type, is fixed to thefirst elevator table 570 such that the air cylinder 626 extends in avertical direction, and is accommodated in a hole formed through thethickness of the Y table 566, such that the air cylinder 626 is movableupwardly and downwardly relative to the Y table 566. When the piston rod628 is extended out by a biasing force of a spring provided in a housingof the cylinder 626, the second elevator table 620 is moved upwardlyrelative to the first elevator table 570. When a compressed air issupplied to an air chamber provided in the housing, the piston rod 628is retracted into the housing whereby the second elevator table 620 ismoved downwardly relative to the first elevator table 570. A lowermovement end position of the second elevator table 620 is defined by astroke end of a piston (not shown) of the air cylinder 626.

[0106] As shown in FIG. 20, on the second elevator table 620, there areprovided a main positioning pin (not shown) and an auxiliary positioningpin 632 which cooperate with each other to position the ceramicsubstrate 522 on a horizontal plane. The main and auxiliary positioningpins 632 are provided on the side of the fixed guide 590. The mainpositioning pin is fixed to the second elevator table 620, while theauxiliary positioning pin 632 is provided on the second elevator table620 such that the auxiliary positioning pin 632 is movable in the X-axisdirection. A guide rail 634 is fixed to the second elevator table 620such that the guide rail 634 extends in the X-axis direction, and ablock member 636 is fitted on the guide rail 634 such that the blockmember 636 is movable in the X-axis direction. The auxiliary positioningpin 632 is fixed to the block member 636, so that the auxiliarypositioning pin 632 is movable toward and away from the main positioningpin in the X-axis direction. The position of the auxiliary positioningpin 632 is adjusted depending upon the size of the ceramic substrate522.

[0107] A board supporting device 640 is fixed in a predeterminedposition on the second elevator table 620, so that the ceramic substrate522 can be supported at its lower surface by the board supporting device640. This board supporting device 640 is provided in an area which isdefined by a two-dot chain line in FIG. 2. The board supporting device640 may be constructed to include the backup pin 372 and the pinsupporting member 374 as in the embodiment illustrated in FIGS. 1-13, ormay be constructed to include the plurality of supporting members 410,412 as in the embodiment illustrated in FIGS. 15-18. Or alternatively,the board supporting device 640 may be constructed to include aplurality of supporting members each having a suction portion whichsupports the ceramic substrate 522 with application of a vacuum pressureto the substrate 522. In any one of these cases, a lower one 644 ofopposite surfaces of the ceramic substrate 522 constitutes a supportedsurface at which the ceramic substrate 522 is to be supported by theboard supporting device 640, while the other of the opposite surfaces,i.e., an upper surface 647 of the ceramic substrate 522 constitutes awork surface onto which the electric component (not shown) is to bemounted.

[0108] As is apparent from the enlarged view of FIG. 21, each of theprojecting members 610 has, in its upper end portion, a supportingportion 660 which projects horizontally inwardly of the conveyor belt606. An elastically deformable portion 662 is integrally formed on anupper surface of the supporting portion 660 (which surface is opposed tothe ceramic substrate 522). The elastically deformable portion 662 isformed of a rubber having a certain degree of an electric conductivity.Further, an elastically deformable portion 668 is integrally formed on alower end portion of each of the hold-down portions 594, 596 whichportion is opposed to the conveyor belt 606. FIG. 21 illustrates theelastically deformable portion 668 provided in the hold-down portion594. In the present embodiment, each of the projecting members 610constitutes a movable member, while each of the hold-down portions 594,596 constitutes a receiving member. The projecting members 610 as themovable members and the holding-down portions 594, 596 as the receivingmembers cooperate with one another to constitute a substrate clampingdevice. The rubber having a certain degree of electric conductivity isone example of a rubber or its equivalent material which are preferablyused for forming the elastically deformable portions 662, 668.

[0109] The present electronic-component mounting system is controlled bya control device 680 (see FIG. 19), to which there are connected theX-axis servomotors 538, 554, the Y-axis servomotor 562 and (the controlvalves of) the air cylinders 586, 626.

[0110] When the ceramic substrate 522 is to be loaded onto the boardpositioning and supporting device 546, the conveyor belts of the boardloading device and the board positioning and supporting device 546 aredriven or circulated. In this instance, the first elevator table 570 isheld in its upper movement end position, while the second elevator table620 is held in its lower movement end position. Thus, as the conveyorbelts are circulated, the ceramic substrate 522 is loaded onto the boardpositioning and supporting device 546 from the board loading device. Theloading movement of the ceramic substrate 522 is stopped by a stopper(not shown) which is positioned in an operative position. After theconveyor belts 606 are stopped, the second elevator table 620 is movedupwardly relative to the first elevator table 570. When the secondelevator table 620 is being elevated, the second elevator table 620 isbrought into engagement with the engaging pins 614, thereby causing theprojecting members 610 to be moved upwardly against the biasing forcesof the coil springs 612, and then lifting the ceramic substrate 522 upaway from the conveyor belts 606. As the second elevator table 620 iselevated, the main and auxiliary board positioning pins 632 and theboard supporting device 640 are elevated, so that the positioning pinsare fitted in a main positioning hole (not shown) and an auxiliarypositioning hole 674, for thereby positioning the ceramic substrate 522relative to the second elevator table 620. When the ceramic substrate522 is thus poisoned relative to the second elevator table 620, theceramic substrate 522 is supported at its lower surface 644 by the boardsupporting device 640 which are brought into contact with the lowersurface 644. When the ceramic substrate 522 is lifted up by theprojecting members 610 and then brought into contact with the hold-downportions 594, 596, the board supporting device 640 is also brought intocontact with the ceramic substrate 522 while the main and auxiliarypositioning pins 632 are fitted into the main and auxiliary positioningholes 674 to position the ceramic substrate 522 relative to the secondelevator board 620. In other words, the ceramic substrate 522 ispositioned by the main and auxiliary board positioning pins 632, whilethe ceramic substrate 522 is gripped by the hold-down portions 594, 596and the projecting members 610 and is also supported at its lowersurface 644 by the board supporting device 640. In the presentembodiment, since the contact portions of the hold-down portions 594,596 and the projecting members 610 are provided by the elasticallydeformable portions 662, 668, it is possible to avoid stressconcentration in a local portion or portions of the contact surfaces ofthe ceramic substrate 522 at which the ceramic substrate 522 is broughtinto contact with the hold-down portions 594, 596 and the projectingmembers 610, thereby avoiding damaging of the ceramic substrate 522.Further, since the elastically deformable portions 662, 668 are made ofthe rubber having the electric conductivity, the ceramic substrate 522can be prevented from being electrified while being clamped.

[0111] The air cylinder 626 may be a double acting cylinder, as theabove-described clamp cylinder 350. In this case, a variable flowregulator valve having the same construction as the above-describedvariable flow regulator valve 366 may be provided in an air passagewhich communicates a rod-side chamber of the air cylinder 626 with anair source, while an electromagnetically-operated proportional controlvalve having the same construction as the above-described proportionalcontrol valve 368 may be provided in an air passage which communicates ahead-side chamber of the air cylinder 626 with the air source. Oralternatively, the variable flow regulator valve and theelectromagnetically-operated proportional control valve may be providedin the air passage which communicates the head-side chamber of the aircylinder 626 with the air source, such that the flow regulator valve andthe proportional control valve are located near the head-side chamberand the air source, respectively. In either case, the variable flowregulator valve can be controlled by the control device 680 such thatthe flow regulator valve is choked in a final stage of the upwardmovement of the second elevator table 620, whereby the velocity of theupward movement of the second elevator table 620 (and accordingly thevelocity of the upward movement of the projecting members 610) can bereduced. Thus, the projecting members 610 can be brought into abuttingcontact with the ceramic substrate 522 with a reduced impact. Further,the valve-opening pressure of the electromagnetically-operatedproportional control valve can be set at a suitable value dependingupon, for example, the thickness of the ceramic substrate 522, forthereby making it possible to appropriately control a clamping force ofthe projecting members 610.

[0112] It is also possible to form a coating layer such as a diamondcoating (DLC) on side surfaces of the fixed and movable guides 590, 592,i.e., guide surfaces for guiding the ceramic substrate 522. Further, itis also possible to form an elastically deformable portion made of arubber or its equivalent material, on a contact surface of theabove-described stopper which is brought into contact with the ceramicsubstrate 522 to stop the movement of the ceramic substrate 522 in thesubstrate positioning and supporting device 546.

[0113] The substrate holding device of the present invention can beemployed also in an electronic-component mounting system in which afragile-material-made substrate is linearly moved in a predetermineddirection while a mounting head (suction head) is linearly moved in adirection that is perpendicular to the predetermined direction in aplane, or an electro-component mounting system in which afragile-material-made substrate is fixed in a predetermined positionwhile a mounting head is moved to be positioned in a desired position ina plane. Where a head moving device carries and moves carries aplurality of mounting heads in a plane, each mounting head may beadapted to be immovable in a direction parallel to the plane, oralternatively, the head moving device may be adapted to move a mountingdevice (in which the plurality of mounting heads are rotated about acommon axis and are sequentially positioned in each of operationpositions) in a desired position in a plane.

[0114] Further, the substrate holding device of the present inventioncan be employed also in a board work system (adhesive applying system)equipped with a working head (applying head) capable of applying anadhesive as a highly viscous fluid to a circuit substrate, as describedin JP-A-H09-75830.

[0115] While the several embodiments of this invention have beendescribed above in detail, for illustrative purpose only, it is to beunderstood that the present invention may be embodied with various otherchanges and modifications, such as those described in theabove-described “SUMMARY OF THE INVENTION”, which can be made on basedon knowledge of those skilled in the art.

1. A substrate holding device for holding a circuit substrate, saidsubstrate holding device comprising: a substrate clamping deviceincluding a receiving member and a movable member which forces a portionof the circuit substrate against said receiving member, for therebyclamping the circuit substrate, wherein at least one of said receivingmember and said movable member has an elastically deformable portionformed of a rubber or its equivalent material and provided by a contactportion thereof which is to be brought into contact with the circuitsubstrate.
 2. A substrate holding device according to claim 1, whereinsaid elastically deformable portion is formed of a rubber or itsequivalent material which has an electric conductivity.
 3. A substrateholding device according to claim 1, comprising: an actuator whichactuates said movable member; and a movement-velocity controlling devicecontrolling a movement velocity of said movable member actuated by saidactuator.
 4. A substrate holding device according to claim 3, whereinsaid movement-velocity controlling device has a velocity reducingportion which reduces the movement velocity of said movable member in afinal stage of forward movement of said elastically deformable portionof said movable member toward said receiving member.
 5. A substrateholding device according to claim 4, wherein said velocity reducingportion gradually reduces the movement velocity of said movable memberto substantially zero.
 6. A substrate holding device according to claim3, wherein said actuator is an air cylinder, and wherein saidmovement-velocity controlling device includes an air-flow-ratecontrolling device controlling a flow rate of air to be supplied to saidair cylinder.
 7. A substrate holding device according to claim 6,wherein said air-flow-rate controlling device includes a variable flowregulator valve, and a regulator-valve controlling device whichregulates said variable flow regulator valve in a final stage of forwardmovement of said elastically deformable portion of said movable membertoward said receiving member.
 8. A substrate holding device according toclaim 1, comprising: an actuator which actuates said movable member; andan actuation-force controlling device controlling an actuation forcewith which said movable member is actuated by said actuator.
 9. Asubstrate holding device according to claim 8, wherein saidactuation-force controlling device controls said actuation force suchthat said actuation force is equalized to one of a plurality ofdifferent amounts which are predetermined for a plurality of kinds ofcircuit substrates to be clamped.
 10. A substrate holding deviceaccording to claim 9, wherein said actuator is an air cylinder, andwherein said actuation-force controlling device includes an air-pressurecontrolling device controlling a pressure of air to be supplied to saidair cylinder.
 11. A substrate holding device according to claim 1,wherein said circuit substrate is a rectangular plate, and wherein saidreceiving member and said movable member grip two portions of saidcircuit substrate which portions are located along two mutually-parallelsides of said circuit substrate.
 12. A process of fabricating anelectric circuit, by mounting a plurality of electric components onto afragile-material-made substrate such as a ceramic substrate by amounting device, while fixing said substrate to said mounting device bycausing an elastically deformable portion of a movable member formed ofa rubber or its equivalent material, to force a peripheral portion ofthe ceramic substrate against an elastically deformable portion of areceiving member formed of a rubber or its equivalent material.